A soft, supple and flexible skin has a marked cosmetic appeal. As human skin ages with advancing years, the epidermis can become folded, ridged or furrowed to form wrinkles. These signal loss of youthful appearance and herald the transition to old age. Exposure to excessive doses of sunlight accelerates the transition process. Moreover, the outer layer of the epidermis known as the stratum corneum can become dry and flaky following exposure to cold weather or excessive contact with detergents or solvents.
Science has discovered a few active substances which can counter the aging process. Among these are the retinoids and the alpha-hydroxy carboxylic acids. Unfortunately these active substances can be incompatible under certain conditions. Retinol rapidly degrades in a acidic environment that may be most conducive to the alpha-hydroxys. Combinations of these actives have been reported in U.S. Pat. No. 5,935,589 (Mukhedjee et al.) which places the actives in separate emulsions within a single composition. Retinol is stabilized at a neutral pH in an oil-in-water emulsion. An alpha-hydroxy carboxylic acid such as glycolic acid is dispersed within a water-in-oil emulsion. Both of these emulsions are then carefully combined to form a single cosmetic composition. A problem for such compositions is that over time there will be leakage between the separate emulsions resulting in retinol degradation.
Treatments designed to prolong or promote youthful appearance of skin include topical applications of cosmetic preparations, lotions and moisturizers. Many skin care compositions have been created to treat wrinkles and fine lines and restore the youthful appearance of skin, and most of these are intended to improve the skin's surface characteristics, for example, to minimize environmental effects and stress on the skin, improve texture, firmness and elasticity, counteract dryness, smooth out wrinkles, minimize age spots, improve color, and increase moisture content of the skin. However, in many cases the different active ingredients used to treat the various different causes of aging can react together causing these active ingredient to degrade and/or lose their efficacy over time. As a result, it has been necessary to provide different active ingredients for the treatment of the different causes of aging in numerous bottles, each of which can be applied separately to the skin. The application of these active ingredients from numerous bottles can be cumbersome and inconvenient for the user.
A more direct solution is placement of the different actives into compositions held in separate compartments of a dispenser. Illustrative is U.S. Pat. No. 5,914,116 (Suares et al.) disclosing releasably lockable stackable jars and dual compartment pumps. These packages are designed to deliver the separate actives at different times rather than through simultaneous dosing. In U.S. Pat. No. 5,137,178 (Stokes et al.) a dual compartmented squeezable cosmetic dispenser is disclosed which allows for simultaneous extrusion of separate composition streams.
While each of the aforementioned systems have their particular advantage, they introduce certain disadvantages. Actives placed in dual stream dispensing compartments must be doubly concentrated. Only half of each stream contributes to the final dispensed combined stream concentration. For instance, delivery of 8% alpha-hydroxy carboxylic acid requires a 16% concentrated stream from an equally dispensing dual stream package. High concentration presents problems. Significant skin irritation and erythema may result from localized, non-fully mixed deposition of the stream onto the skin. Internal stability at high concentration may also be compromised. There is need for a better solution.
WO 98/50012 (Noordam et al.) discusses the problem of stabilizing a low pH emulsion of Vitamin C to prevent oxidation of the active. Stabilization is achieved by placing a relatively concentrated aqueous Vitamin C composition in one compartment of a multi-compartment dispensing system. A second compartment contains a cosmetic carrier composition. When ready for use, a small volume of the Vitamin C concentrate is dispensed alongside a larger volume of the carrier base, each being expressed from a separate compartment.
A similar approach has been disclosed by Airspray™ in product brochure literature for their Symbio dual-chamber dispenser. Two non-compatible ingredients are separated each from the other until the moment of application. The Symbio package has two separate chambers each connected to its own pump, one of the chambers being smaller and arranged to deliver a concentrate of an unstable cosmetic substance. Among the unstable substances mentioned are Vitamin A (retinol), Vitamin C (ascorbic acid) and Vitamin E (alpha-tocopherol). There is no suggestion that the larger container included any skin actives other than some enzymes and pigmentation control agents. The technology does not present a solution for delivering actives from a dual compartment in a manner that provides nearly identical stored and skin delivered concentrations. Focus is rather upon an active that is stored highly concentrated but delivered dilute.
Some ingredients used in topical products are potentially irritating, especially to people with “sensitive skin.” For example, chemical skin peeling agents, such as hydroxy acids (HAs), have been proven to deliver cosmetic benefits, such as improvement in the appearance of photodamaged or naturally aged skin, skin lightening, treatment of age spots, etc. Unfortunately, their use at high concentrations may be associated with skin irritation, e.g. skin redness and stinging sensation upon application. The irritation can be ameliorated by lowering the amount of an active ingredient in the composition or by reducing the active's penetration through the skin. A serious drawback of both approaches is that the efficacy is impaired. The HA related irritation can be reduced by raising the composition's pH but this method yields reduced efficacy due to a decreased HA penetration through the skin. It is desirable to reduce or eliminate the irritation potential of HAs while maintaining their efficacy.
Besides performance in reducing signs of skin aging itself, a number of additional issues underlie the development of a successful anti-aging cosmetic formulation, such as those of skin tolerance, pleasant odor, visually appealing and pleasant feeling texture and shelf life or stability.
Accordingly, it is an object of the present invention to provide an anti-aging composition and means of packaging that may facilitate ease of use, long-term storage, and/or efficacy of the anti-aging skin care composition. Moreover, it is an object of the present invention to provide a multi-chamber packet, which contains an anti-aging skin care composition, and to an anti-aging kits which allow for safe application of an anti-aging composition for the treatment or prevention of age-related skin symptoms.